Bill English says he's satisfied with the agreement National has reached with New Zealand First but "we'll have to wait and see" who Winston Peters chooses.

National MPs are meeting in person at Parliament ahead of this afternoon's announcement from Winston Peters, who is poised to reveal which party he'll support.

The agreement National has reached with New Zealand First would be able to form the basis of "a strong and cohesive" government, party leader Bill English says.

However, he still has "no indication" of who Winston Peters will choose when the New Zealand First leader announces his decision on a coalition partner this afternoon.

It's understood Labour is in a similar position.

Bill briefly spoke to media as he headed into a caucus meeting at Parliament to update his National Party colleagues.

"We have had a period of intensive negotiations and I'm satisfied that the agreement we've reached with New Zealand First would be able to form the basis of a strong and cohesive government," he says.

National would "have to wait and see" whether Winston felt the same though.

"Mr Peters has indicated that he's going to announce his position later in the day and, like everyone else, we look forward to hearing what that is."

On arriving at Parliament this morning, a senior National Party minister and a member of the negotiating team, Steven Joyce, said his party did not know any details about how this afternoon's announcement would be made.

"No I haven't had any, I assume that's something Mr Peters will be sharing with us all in due course."

Steven says whether this morning's caucus meeting would include ratification of any deal was "up to the Prime Minister".

But the caucus meeting was to uphold an undertaking to MPs that they would be "updated" before any final decision was made, says Steven.

Heading into this morning's caucus meeting, the New Zealand First MP Shane Jones, was leaving the questions to Winston.

Asked how he was feeling today, he replied, "I feel like a pipiwharauroa" - which translates to shining bronze cuckoo in te reo Māori.

Labour's MPs were also being briefed on the latest developments by teleconference at 11am.

Announcement follows nearly two weeks of talks

Winston announced yesterday that his party would be in a position to make their decision public this afternoon.

In a statement, he says he had advised the leaders of National and Labour of the timing of the announcement.

He says he had advised them of "other matters", but was not specific about what they were.

Last night, National Party leader Bill English says there could be further negotiations with New Zealand First this morning.

It's understood Labour is in a similar position and its executive council has not yet been convened to sign off any potential final deal with New Zealand First.

It is also understood ministerial positions were discussed at one-on-one talks Mr Peters held with both Mr English and Ms Ardern on Tuesday night.

It was still not clear how much notice, National or Labour would get prior to the announcement about Winston's decision.

The Greens were meanwhile waiting to see if New Zealand First would go with Labour before convening its 150-strong Special General Meeting so as not to risk the contents of their deal with Labour being leaked.

-RNZ